Weft yarn storing, feeding and measuring device, preferably for jet weaving machines

ABSTRACT

This device has a stationary storage durm (2) onto which an intermediate yarn store is wound by a winding-on device (3) and from which the yarn (WY) is withdrawn spiralling around the withdrawal end of the storage drum. The device also has a plurality of yarn stopping devices (10) being arranged at angular intervals around the storage drum, said yarn stopping devices consisting of yarn stopping elements (14) and of actuator means (11) moving said stopping elements into and out of the path of the yarn being withdrawn, and an actuator control device (8) adjustable to desired yarn lengths to be withdrawn, said control device transmitting actuating signals to said plurality of yarn stopping devices. The control device (8) comprises storing means (20) for storing an information regarding the yarn stopping device actuated at the end of the next preceding yarn withdrawal cycle, and calculating means (20) for determining a selected series sequence of said yarn stopping devices to be alternately actuated and de-actuated consecutively during the yarn withdrawal cycle on the basis of said stored information and of an adjustable input information for the calculating means representing at least one significant parameter for the distance/time function of the weft yarn insertion process cycle. The calculating means (20) also determines the yarn stopping device to be kept actuated at the end of the present weft yarn withdrawal cycle at last one in said selected series sequence of alternately actuated and de-actuated yarn stopping devices, on the basis of said stored information and of an input information representing said desired yarn length.

The present invention relates to a weft yarn storing, feeding andmeasuring device, preferably for jet weaving machines, in accordancewith the generic clause of claim 1.

DE-OS No. 31 23 760 (which corresponds to U.S. Pat. No. 4,407,336)discloses a yarn storing, feeding and measuring device for jet weavingmachines having a stationary storage drum onto which an intermediateyarn store is wound by a winding-on device and from which the yarn iswithdrawn spiralling around the withdrawal end of the storage drum, yarnsensing means being arranged such that the yarn is passing its detectionarea during withdrawal from the drum, said yarn sensing means producingpulse signals, each pulse signal indicating that the yarn passes adetection area of the yarn sensing means, a plurality of yarn stoppingdevices being arranged at angular intervals around the storage drum,said yarn stopping devices consisting of yarn stopping elements andactuator means moving said stopping elements into and out of the path ofthe yarn being withdrawn, and an actuator control device adjustable todesired weft yarn lengths to be withdrawn, said control device beingresponsive to said pulse signals in such a way that an actuating signalis transmitted to a yarn stopping device the angular position of whichcorresponds to the position rendered by the yarn when said desired yarnlength has been withdrawn. The yarn sensing means consists of aplurality of yarn sensors, each of these sensors being associated with ayarn stopping device. Hence, the number of yarn sensors required forsuch a device corresponds to the number of yarn stopping devices. Yarnstoring, feeding and measuring devices of this kind not only serve tointermediately store the weft yarn on a storage drum, but also serve tosupply the jet weaving machine with a weft yarn length of a desiredvalue. For the latter purpose, this known device carries out thefollowing steps in order to obtain the desired yarn length for each weftyarn insertion into the shed of the weaving machine:

After releasing or de-actuating the yarn stopping device actuated at theend of a previous yarn withdrawal cycle, the yarn is withdrawnspiralling around the withdrawal end of the storage drum. Thereby, theyarn subsequently passes the detection area of each of the several yarnsensors being arranged at the withdrawal end of the storage drum in aspaced, angular relationship with respect to each other. Each yarnsensor generates a pulse signal indicating that the yarn passes itsdetection area, these pulse signals being fed to the control device.Hence, the control device receives a number of pulse signals, thisnumber corresponding to the number of yarn sensors being passed by theyarn during the withdrawal from the storage drum. By counting thesepulse signals received from the yarn sensors, the control devicegenerates a count value corresponding to the actual position of thewithdrawal point of the yarn with respect to the yarn sensors. The countvalue corresponds to the length of yarn having been withdrawn from thestorage drum. When the count value corresponds to the desired yarnlength to be withdrawn, the control device actuates the stopping devicebeing located with respect to the angular movement of the withdrawalpoint of the yarn behind the yarn sensor which generated the last pulsesignal. Thereby, the withdrawal of the yarn is stopped so that thedesired yarn length is obtained. This known yarn storing, feeding andmeasuring device is costly and complicated due to the great number ofyarn sensors required to achieve a sufficiently great number ofdifferent yarn lengths, or in other words to achieve a sufficientlygreat accuracy in the desired weft yarn length. A further drawback iscaused by the fact that yarn sensors are also sensitive in operation,since they usually comprise optical elements which can be covered bylintor be disturbed by irrelevant light rays. If one of the several yarnsensors is e.g. covered by lint, it will no longer generate pulsesignals when the yarn passes its detection area resulting in a wrongcount value in the control device. Hence, the respective yarn length ofthe inserted weft yarn will become greater than the desired yarn length.

DE-OS No. 31 23 760 also discloses a yarn storing, feeding and measuringdevice using only one yarn sensor for detecting the withdrawal of onecomplete yarn winding from the storage drum. In order to be able toadjust the weft yarn length to be withdrawn, this prior art device makesuse of a storage drum, the diameter of which can be mechanically varied.The same concept is disclosed in FR-A No. 2 166 332 and PCT-A WO82/04446. A mechanical adjustment of the diameter of the storage drum,however, calls for complicated mechanical means, which makes the devicecostly and liable to malfunctions.

The object of the present invention is to provide a yarn storing,feeding and measuring device, which does not have said mechanicaldiameter adjustment means and is more reliable than the prior artdevices as described above.

This object is achieved in accordance with the invention in that saidcontrol device comprises storing means for storing an informationregarding the yarn stopping device actuated at the end of the nextpreceding yarn withdrawal cycle and calculating means for determining aselected series sequence of said yarn stopping devices to be alternatelyactuated and de-actuated consecutively during the yarn withdrawal cycleon the basis of said stored information and of an adjustable inputinformation for the calculating means representing at least onesignificant parameter for the distance/time function of the weft yarninsertion process cycle, said calculating means also determining theyarn stopping device to be kept actuated at the end of the yarnwithdrawal cycle as last one in said selected series sequence ofactuated and de-actuated yarn stopping devices, on the basis of saidstored information and of an input information representing the desiredweft yarn length.

In a preferred embodiment of the present invention as claimed in claim2, said significant parameter for the distance/time function of the weftyarn insertion process cycle is the desirable speed value for the weftyarn during said cycle. However, within the scope of the invention, itwould also be possible to provide or set the calculating means of thecontrol device with adjustable input information representing thedesirable value of the deceleration of the weft yarn during the lastphase of the weft insertion cycle, so as to achieve an optimally "soft"deceleration of the weft yarn. Analogously, it would also be possible toset the calculating means with adjustable input information representingthe desirable value of the acceleration of the weft yarn during theinitial phase of the weft insertion cycle.

A preferred embodiment of a yarn storing, feeding and measuring devicein accordance with the present invention will now be described in detailwith reference to the enclosed drawings, where

FIG. 1 shows a side view of the yarn storing, feeding and measuringdevice in partially cut- and cross-sectional representation;

FIG. 2 shows a front view of the device as shown in FIG. 1;

FIGS. 3 and 4 show details of the device shown in FIG. 1 and 2;

FIG. 5 shows a circuit diagram of the actuator control device of themeasuring device shown in FIGS. 1-4;

FIG. 6 shows a flow-diagram used in a microprocessor of the actuatorcontrol device as shown in FIG. 5.

FIG. 7 shows a schematic diagram of a sequence control according to thepresent invention, where the calculating means of the actuator controldevice is set with information regarding desirable values ofacceleration, maximum speed as well as deceleration of the weft yarnduring the whole weft insertion cycle.

Referring now to FIG. 1, a yarn storing, feeding and measuring device 1consists of a storage drum 2, a winding-on device in the form of anorbiting feeder tube 3 and an electric motor 4 for driving this orbitingfeeder tube. A weft yarn WY being supplied from a yarn spool (now shownhere) to the orbiting feeder tube 3 driven by the motor 4 is wound ontothe storage drum 2 and forms there an intermediate yarn store of severalyarn windings. The storage drum 2 is here a stationary part being keptin stationary position with respect to the surroundings by magneticmeans (not shown here). Devices of this type are well-known to the manskilled in the art, for example by U.S. Pat. No. 3,776,480 and by U.S.Pat. No. 3,853,153. The feeding device 1 is provided with a yarn storesensor 5, sensing the amount of yarn stored on the drum 2, which sensoris located close to the generally cylindrical surface of the storagedrum 2. This store sensor 5 can be a so called maximum sensor preferablyconsisting of a light emitting device and a light receiving device. Theyarn store sensor 5 generates a signal indicating the amount of yarnstored on the drum, i.e. in principle the number of windings of yarnstored on the drum. Based on this signal, a store control unit 7controls the operation of the electric motor 4 in such a way that thereis continuously a sufficient amount of yarn available on the yarnstorage drum 2. Yarn store control units are per se well-known to theman skilled in the art. This art can be exemplified by DE-OS No. 29 08743, FR-A No. 1 562 223 and U.S. Ser.No. 584,436 (Applicant's own).

A yarn stopping device 10 located at the withdrawal end of the storagedrum 2 consists of an actuator means 11 comprising a plurality ofelectromagnetic coils 11 being wound around a coil core 12 supported ofa balloon limiting ring 13 consisting of two U-shaped rings coveringsaid plurality of electromagnetic coils 11. Said balloon limiting ring13 is fixedly secured to the stationary part of the storing device 1,for example to a base plate thereof. A ring-shaped guiding portion 16 isconnected to the withdrawal end of the storage drum 2. Said guidingportion 16 supports a plurality of yarn stopping elements 14, each ofsaid yarn stopping elements 14 consisting of a metal ball 14 beingmovably disposed in a radial bore 15 provided in the guiding portion 16.

As shown in FIGS. 3 and 4, the respective electromagnetic coils 11 andassociated cores 12 are arranged opposite to said bores 15. The balloonlimiting ring 13 and the guiding portion 16 define a gap 18 beingpreferably in the order of 1-2 millimeters. The weft yarn WY passes saidgap when being withdrawn from the storage drum 2. A permanent magnet 17is located at one end of each bore 15 for moving back said metal ball 14into said bore 15 after switching off an actuation current fed to therespective electromagnetic coils 11. As shown in FIGS. 3 and 4, themetal ball 14 is attracted by the magnetic force of the coil 11 whenswitching on the actuation current fed to the coil 11. The width of thegap 18 corresponds to the radius of the metal ball 14. When the coil 11is not actuated, the permanent magnet 17 will attract the metal ball 14,so that the ball will be completely positioned inside the bore 15,whereby the yarn WY can be freely withdrawn in the axial direction fromthe storage drum 2 and inserted into the shed of the weaving machine.

The magnetic force of each electromagnetic coil 11 is chosen such thatthis force will overcome the attraction force of the permanent magnet 17when feeding the actuation current to the coil 11. The metal ball 14will thereby move outwardly in the radial direction of the bore 15 andcome into contact with the free end of the coil core 12. In this state,approximately half the metal ball locks the gap 18 for the passage ofthe yarn WY in such a way that the withdrawal of the yarn from thestorage drum 2 is prevented. When switching off the actuation currentfed to the coil 11, the tension in the yarn WY, being pulled by the weftinsertion means of the weaving machine, co-acts with the magnetic forceof the permanent magnet 17 such that the metal ball 14 will return toits starting position so as to come into contact with the permanentmagnet 17. As the tension of the yarn co-acts with the magnetic force ofthe magnet 17 due to the shape of the metal ball 14, the holding forceof the permanent magnet 17 can be relatively small. Hence, only a smallportion of the attracting force generated by the electromagnetic coil 11is required for overcoming the magnetic force of the permanent magnet17. For this reason, the yarn stopping device 10 is working faster thanprior art devices using stopping elements 14 which are needle-shaped orpin-shaped. For further enhancing the operation of the yarn stoppingdevice 10, a thin plate of non-magnetic material can be positioned atthe outer end of the permanent magnet 17 and/or on the free end of thecoil core 12 for eliminating a magnetic sticking or "adhesion" effectbetween the metal ball 14 and the permanent magnet 17 and/or the coilcore 12.

The stopping element 14 can also have the form of a short cylindricalpin with a plane inner end directed to the permanent magnet 17 and arounded, preferably semi-spherical outer end.

Referring now to FIG. 5, the presently preferred embodiment of theactuator control device 8 will hereinafter be described in detail. Thisdevice 8 comprises a calculating means 20, which is a standardmicroprocessor, here of the type 8748, manufactured by the INTEL Corp.,U.S.A.

The microprocessor 20 is supplied with sync signals generated by acrystal resonator 31 connected to input pins "XTAL" of themicroprocessor.

A trigg-input 32 receives a signal picked up at the main shaft of theweaving machine. This signal is applied to the input of anopto-electronical coupling element 33, the output of which is connectedto input pin TO of the microprocessor 20. The trigg-signal serves tosynchronize the operation of the loom with the operation of themicroprocessor 20 controlling the yarn storing, feeding and measuringdevice 1. More particularly, the occurrence of a trigg-signal on input32 indicates that the next weft yarn insertion cycle starts.

In the actuator control device 8 there is provided, in accordance withthe present invention, a combined weft yarn insertion speed/yarn lengthsetting switching device, preferably consisting of three BCD-switches34-36 and a Hexa-decimal code switch 37, each of these switches havingfour input terminals and one output terminal. Each of the BCD-switchescan be set to a decimal number from 0-9, and the Hexa-decimal codeswitch from 0-F(=16). This decimal resp. hexa-decimal number isconverted by the respective switch such that the corresponding one ofits four input terminals is connected to its output terminal inaccordance with the code. When for example setting one of theBCD-switches to the decimal number "5", then its first and third inputterminal is connected to its output terminal, whereas its second andfourth input terminal is disconnected from the output terminal. Therespective first input terminals of the switches 34-37 are connected viadiodes to pin DB3 of the microprocessor 20, the respective second inputterminals of the switches are connected via diodes to pin DB2 of themicroprocessor, the respective third input terminals of the switches areconnected via diodes to pin DB1 of the microprocessor and the respectivefourth input terminals of the switches are consequently connected viadiodes to pin DB0 of the microprocessor 20. The respective outputterminals of the switches 34-37 are connected to output pins P40-P43 ofan expansion circuit 38, here a standard circuit INTEL type 8243 ("I/OExpander"), the four input pins of which are designated P20-P23 andwhich are connected to pins also designated P20-P23 of themicroprocessor 20. At the beginning, each of the pins DB0-DB3 of themicroprocessor 20 is in its "high" state, i.e. logical one potential.The pins P20-P23 of the microprocessor 20 are also in the "high" state.For reading the value of one of the switches 34-37, the microprocessor20 pulls down the voltage of one of its pins P20-P23. For example, forreading the BCD value of BCD-switch 34, the microprocessor 20 generatesa certain, predetermined combination of "high" and "low" potential(logical one and zero) on the four pins P20-P23 and on its output pincalled PROG, which is connected to the PROG input pin of the expansioncircuit 38. The expansion circuit 38 will respond to said combination of"high" and "low" potential on its pin P20-P23 and PROG by generating a"low" potential (logical zero) on its output pin P40. In case thedecimal number selected manually by the weaving machine operator onswitch 34 is "5", the potential of pins DB3 and DB1 will be pulled downto "low", whereas the potential on pins DB2 and DB0 will remain "high".For reading one of the other switches, the microprocessor 20 generatesanother predetermined combination of "high" and "low" potential on itsfour pins P20-P23 and on its output pin PROG, whereby the expansioncircuit 38 will generate "low" potential on another one of the pinsP40-P43 leading to the switch to be read.

Output pins P10-P17 of the microprocessor 20 are connected to input pins1-8 of an amplifier or driver circuit 39, this circuit having eightoutput pins 11-18, each of these being associated with a respectiveinput pin 1-8. When receiving "high" potential (logical one) on one itsinput pins 1-8, the driver circuit 39 connects the corresponding outputpin to a voltage source of -35 Volts. Each of the output pins 11-18 ofthe driver circuit 39 is connected to three electromagnetic coils 11.Twenty-four electromagnetic coils 11 associated with twenty-four yarnstopping devices 14 are arranged as a matrix having eight rows and threecolumns. The respective output terminals of the electromagnetic coils 11arranged in one column are connected to a respective one of three outputconductors 40-42.

Output pins P24-P26 of the microprocessor 20 are connected throughcurrent amplifier circuits 43-45 to input pins 1-3 of a further drivercircuit 46. This driver circuit 46 includes three output pins 14-16,each being connected to a respective one of the conductors 40-42. Whenreceiving a "high" potential (logical one) on one of its input pins, thedriver circuit 46 connects the corresponding output pin to a voltage of+5 Volts. Due to the above described matrix circuit arrangement, themicroprocessor 20 is enabled to energize one of the twenty-fourelectromagnetic coils 11 by generating a "high" potential on one theoutput pins P10-P17 determining the row of the coil 11 to be actuated,and by generating a "high" potential on one of its output pins P24-P26selecting the column of the electromagnetic coil 11 to be actuated. Theabove described matrix circuit arrangement allows to actuate oneelectromagnetic coil 11 among the twenty-four electromagnetic coils 11with only eleven output pins P10-P17 and P24-P26 of the microprocessor20 and as many signal wires to the coils 11.

Output pin P51 of the expansion circuit 38 is connected via a currentamplifier or driver circuit 49 to a light-emitting element 50, which inturn is connected to minus via a resistor 51. The light-emitting element50 actuates an opto-sensitive switching element 52 actuating in turn astop-motion relay (not shown here, but well-known to the man skilled inthe art) of the weaving machine.

Output pin P50 of the expansion circuit 38 is connected via said drivercircuit 49 to a relay of the valve for the main air jet nozzle (alsowell-known to the man skilled in the art) of the jet weaving machine.The driver circuits 39 and 49 are standard circuit elements of the typeUDN 2580A. The further driver circuit 46 is also a standard circuitelement of the type UDN 2002. The manufacturer of said standard circuitelements is the SPRAGUE Corp., U.S.A.

Referring now to FIG. 6, there is shown a flow diagram of the controlprogramme stored in the read-only memory of the presently preferredembodiment of the microprocessor 20. When receiving a reset signal, themicroprocessor 20 is reset so as to start the carrying out of theprogamme with the first instruction thereof, being the "START"instruction. This reset signal will be received on reset line 53 andwill pass through a reset interface circuit 54 to the reset pin R of themicroprocessor 20. The reset signal is automatically generated each timethe main power of the weaving machine is switched on, which guaranteesthat the microprocessor begins to carry out the control programme withthe START step after switching on the power of the weaving machine.

At programme step No. 1, the microprocessor 20 actuates a predeterminedyarn stopping device 10 for locking the weft yarn WY is its start ofwithdrawal position. The microprocessor 20 stores the number of theactuated stopping device or its angular position in a predeterminedstorage cell of its RAM (Random Accessary Memory).

At programme step No. 2, the microprocessor 20 reads the hexa-decimalcode of the switch 37 representing a desired, manually set value of theweft yarn insertion speed, and stores this value in a storage cell ofits RAM. At programme step No. 3, the microprocessor 20 consecutivelyreads the BCD code of the switches representing the desired, manuall setweft yarn length and stores this length value is another storage cell ofthe RAM of the microprocessor. At programme step No. 4, themicroprocessor 20 transfers the BCD codes representing the set desiredweft yarn length to a digital value corresponding to the number ofwithdrawal revolutions and 1/24 revolutions of the storage drum 2,whereby this digital value represents the number of revolutions aroundthe storage drum which the withdrawal point of the yarn travels duringone weft yarn insertion cycle, i.e. during withdrawal of the desired,set weft yarn length. On the basis of said digital number, themicroprocessor 20 determines which yarn stopping device shall beactuated by the end of the present weft yarn withdrawal (and insertion)cycle. The number of the determined stopping device is stored in apredetermined storage cell of the RAM of the microprocessor.

At programme step No. 5, there is a waiting routine, causing themicroprocessor 20 to await the receipt of a trigg-signal from theweaving machine, e.g. in the form of a signal representing the actualposition of the main shaft of the weaving machine at the moment when thepresent weft yarn insertion cycle shall start. This trigg-signal can begenerated by a rotary sensor, per se well-known to the man skilled inthe art, reading the angular position of the main shaft of the weavingmachine. This waiting routine is realized by a programme loopperiodically checking whether said trigg-signal occurs. If thiscondition is fulfilled, the microprocessor 20 continues to programmestep No. 6.

At programme step No. 6, the microprocessor 20 generates, by generatinga predetermined combination of "high" and "low" potential on its outputpins P20-P23 and PROG, a "high" potential on output P50 of the expansioncircuit 38, whereby the main air jet nozzle of the weaving machine willbe opened. At programme step No. 7, the yarn stopping device 10 actuatedduring programme step No. 1 is de-actuated for releasing the locked weftyarn for withdrawal from the storage drum 2. From this moment the weftyarn will be pulled by the opened main air jet nozzle and withdrawn fromthe drum 2, whereby the withdrawal point will travel around thecircumference or periphery of the withdrawal end of the drum 2.

In this presently preferred embodiment of the invention, as soon as themicroprocessor 20 has carried out programme step No. 7, themicroprocessor will, in programme step No. 8, actuate the yarn stoppingdevice in the position next before the stopping device that wasde-actuated in programme step No. 7. For example, if there aretwenty-four yarn stopping devices EM₁ -EM₂₄ around the drum 2 andstopping device EM₈ was actuated in programme step No. 1 and de-actuatedin programme step No. 7, yarn stopping device EM₇ will be actuated inprogramme step No. 8.

Programme step No. 9 involves a time delay which varies in dependence onthe set desired weft yarn insertion speed on code switch 37. After thistime delay, the microprocessor 20 continues to programme step No. 10, inwhich the yarn stopping device as actuated in programme step No. 8 willbe de-actuated again, so as to allow the yarn to pass this stoppingdevice during its continued withdrawal from the drum. However, thismeans that the weft yarn cannot pass stopping device EM₇ before a pointof time determined by the set weft yarn speed, that is a kind ofcontinuous control of the yarn withdrawal has been achieved.

At programme step No. 11, the microprocessor 20 examines the conditionwhether the point of time for switching off the valve of the main airjet nozzle has been reached, which point of time has been calculated bythe microprocessor on the basis of the point of time for switching onthe main nozzle, the set weft yarn length and the set weft yarn speed.If this condition is not fulfilled, the microprocessor continues withprogramme step No. 12, in which the microprocessor examines whether thepoint of time for actuating the yarn stopping device determined inprogramme step No. 4 has been reached.

If the condition at programme step No. 11 is fulfilled, themicroprocessor goes to step No. 13, in which it switches off the mainair jet nozzle, before it continues to step No. 12.

If the condition in programme step No. 12 is not fulfilled, themicroprocessor 20 goes back to programme step No. 8, in which it nowactuates the yarn stopping device in the position next before thestopping device that was de-actuated in programme step No. 10, that isin this case stopping device EM₆. The microprocessor 20 then continuesto go through the loop consisting of programme steps No. 9, 10, 11, 12and back to No. 8, until the condition is step No. 12 is fulfilled, thatis until the point of time for actuating the yarn stopping devicedetermined in programme step No. 4 has been reached.

When the condition at programme step No. 12 has been fulfilled, themicroprocessor 20 continues with step No. 14, in which the yarn stoppingdevice as determined during programme step No. 4 is actuated for finallystopping the yarn withdrawal at the end of the weft yarn insertioncycle.

Then, in programme step No. 15, the microprocessor 20 examines whetherthere is still an occurring trigg-signal from the weaving machine. Ifthis signal has meanwhile disappeared, the microprocessor goes back toprogramme step No. 2 again and all the programme steps for carrying outa new weft yarn insertion cycle (withdrawal cycle) are repeated again.

From the description above one can see that by actuating andde-actuating certain predetermined ones of the yarn stopping devicesaround the drum, the de-actuating being carried out at calculated pointsof time as determined by the set weft yarn length, it has becomepossible to keep a reliable control over the whole yarn withdrawalcycle, since the yarn will be permitted to pass the predeterminedstopping devices only when said calculated points of time arerespectively reached.

The present invention is not limited to the embodiment described abovebut several other embodiments are possible within the scope of theinvention, particularly with regard to the selected sequence of yarnstopping devices to be consecutively actuated and de-actuated during theyarn withdrawal cycle.

For example, FIG. 7 shows a schematic diagram of a more advancedsequence control of the yarn stopping devices in accordance with thepresent invention, where the actuator control device has been set withinformation of desirable values of not only weft yarn speed, but also ofacceleration as well as deceleration for the weft yarn. In this advancedembodiment, which however make great demands on very short responsetimes for the stopping devices, the microprocessor de-actuateselectromagnet or stopping device EM₈ at a point of time t=0, whereby theweft yarn starts to be withdrawn from the storage drum 2 of the yarnstoring, feeding and measuring device 1. During the acceleration phase,the microprocessor actuates stopping device EM₁₄ at t=3 ms(milli-seconds), respectively de-actuates same at t=7 ms, whereby theyarn not until the latter moment t=7 ms is permitted to pass thestopping device, which means that the yarn withdrawal during this phasewill be adapted to the desired, set acceleration curve characteristics.For this embodiment of the invention, the setting of desired value ofacceleration calls for an additional code switch, preferably of thehexa-decimal type.

At the end of its acceleration phase the weft yarn is permitted to passthe stopping device EM₂₀ at point of time t=11 ms by de-actuating saidstopping device at this point of time after having been actuated at t=7ms. The weft yarn insertion cycle now enters the phase in which thespeed of the yarn is at the maximum and essentially constant, duringwhich phase the yarn is allowed to pass by turn the stopping devicesEM₂, EM₈ (whereby the yarn withdrawal point has travelled one revolutionaround the drum 2), then EM₁₄, EM₂₀, EM₂, EM₈ (whereby the yarnwithdrawal point has travelled two revolutions around the drum), thenEM₁₄, EM₂₀, EM₂, EM₈ (=three revolutions around the drum) and finallystopping device EM₁₄, that is every sixth stopping device is de-actuated(after respective actuation) in this phase at the following respectivepoints of time: t=14 ms, 16 ms, 18 ms, 20 ms, 22 ms, 24 ms, 26 ms, 28ms, 30 ms, 32 ms and finally t=34 ms.

Now, the weft yarn insertion cycle enters its last phase, in which theyarn shall be retarded in an optimally "soft" way, in this embodiment byde-actuating (after respective actuation) by turn the yarn stoppingdevices EM₁₆, EM₁₈, EM₂₀, EM₂₁ and EM₂₂ at points of time t=35 ms, 36ms, 37 ms, 38 ms respectively at t=39 ms. Setting of a desireddeceleration value also calls for an additional code switch. On thebasis of the set desired weft yarn length, in this case 3 15/24×thecircumference of the drum, the microprocessor of the actuator controldevice has selected (also on the basis that EM₈ was the actuatedstopping device at the end of the next preceding insertion cycle) thatstopping device EM₂₃ shall be actuated for stopping the yarn withdrawalduring the present insertion cycle. Therefore, this stopping device isactuated at point of time t=37 ms and is not de-actuated again until themicroprocessor has received a new trigg-signal from the weaving machinetelling that a new insertion cycle shall start.

1 "ACTUATE STOPPING DEVICE FOR LOCKING YARN IN ITS START POSITION; STORENUMBER OF SAID STOPPING DEVICE"

2 "READ THE CODE SWITCH FOR SET WEFT YARN SPEED; STORE THE SET VALUE"

3 "READ THE CODE SWITCHES FOR SET WEFT YARN LENGTH; STORE THE SET VALUE"

4 "TRANSFER SET WEFT YARN LENGTH TO WITHDRAWAL REVOLUTIONS AND 1/24REVOLUTIONS; CALCULATE WHICH STOPPING DEVICE TO BE ACTUATED NEXT BY ENDOF WITHDRAWAL CYCLE; STORE ITS NUMBER"

5 "TRIG SIGNAL FROM WEAVING MACHINE?"

6 "ACTUATE SOLENOID VALVE FOR MAIN NOZZLE"

7 "RELEASE YARN BY DE-ACTUATING DRAWN STOPPING DEVICE"

8 "ACTUATE STOPPING DEVICE IN POSITION NEXT BEFORE JUST DE-ACTUATEDSTOPPING DEVICE"

9 "TIME DELAY DETERMINED BY THE SET WEFT YARN SPEED VALUE"

10 "DE-ACTUATE DRAWN STOPPING DEVICE IN STEP (7)"

11 "TIME TO CLOSE MAIN NOZZLE?"

12 "TIME TO ACTUATE "LAST" STOPPING DEVICE?"

13 "CLOSE THE MAIN NOZZLE"

14 "ACTUATE THE STOPPING DEVICE DETERMINED AT STEP (4)"

15 "TRIG SIGNAL FROM WEAVING MACHINE?"

I claim:
 1. Yarn storing, feeding and measuring device, particularly forjet weaving machines, having a stationary storage drum (2) onto which anintermediate yarn store is wound by a winding-on device (3) and fromwhich the yarn (WY) is withdrawn spiralling around the withdrawal end ofthe storage drum, a plurality of yarn stopping devices (10) beingarranged at angular intervals around the storage drum, said yarnstopping devices consisting of yarn stopping elements (14) and ofactuator means (11) moving said stopping elements into and out of thepath of the yarn being withdrawn, and an actuator control device (8)adjustable to desired yarn lengths to be withdrawn, said control devicetransmitting actuating signals to said plurality of yarn stoppingdevices, characterized in that said control device (8) comprises storingmeans (20) for storing an information regarding the yarn stopping deviceactuated at the end of the next preceding yarn withdrawal cycle andcalculating means (20) for determining a selected series sequence ofsaid yarn stopping devices to be alternately actuated and de-actuatedconsecutively during the yarn withdrawal cycle on the basis of saidstored information and of an adjustable input information for thecalculating means representing at least one significant parameter forthe distance/time function of the weft yarn insertion process cycle,said calculating means (20) also determining the yarn stopping device tobe kept actuated at the end of the present weft yarn withdrawal cycle aslast one in said selected series sequence of alternately actuated andde-actuated yarn stopping devices, on the basis of said storedinformation and of an input information representing said desired yarnlength.
 2. Device as claimed in claim 1, characterized in that saidsignificant parameter for the distance/time function of the weft yarninsertion process cycle is the speed of the weft yarn (WY) during saidcycle, and in that said selected series sequence of yarn stoppingdevices (14) is de-actuated at points of time determined by the setdesired value of the weft yarn speed.
 3. Device as claimed in claims 1or 2, characterized in that said storing and calculating means (20)consists of a microprocessor.
 4. A yarn storing, feeding and measuringdevice, particularly for jet weaving machines, having a stationarystorage drum onto which an intermediate yarn store is wound by awinding-on device and from which the yarn is withdrawn spiralling aroundthe withdrawal end of the storage drum, a plurality of yarn stoppingdevices being arranged at angular intervals around the storage drum, anda control device transmitting actuating signals to said plurality ofyarn stopping devices, wherein said control device comprises storingmeans for storing information regarding the yarn stopping deviceactuated at the end of the last yarn withdrawal cycle, and calculatingmeans for determining, on the basis of said stored information, a seriessequence of yarn stopping devices to be alternately actuated andde-actuated during said yarn withdrawal cycle, and for determining, onthe basis of said stored information, the yarn stopping device to bekept actuated at the end of the present weft yarn withdrawal cycle.
 5. Ayarn storing, feeding and measuring device as claimed in claim 4,wherein said control device comprises a first input section forinputting information concerning the desired yarn length to be withdrawnfrom the storage drum during each yarn withdrawal cycle.
 6. A yarnstoring, feeding and measuring device as claimed in claim 5, whereinsaid control device comprises a second input section for inputtinginformation concerning the yarn withdrawal speed.
 7. A yarn storing,feeding and measuring device as claimed in claim 5, wherein saidcalculating means determines, on the basis of stored information and onthe basis of said information concerning the desired yarn length, saidyarn storing device to be kept actuated at the end of the present weftyarn withdrawal cycle.
 8. A yarn storing, feeding and measuring deviceas claimed in claim 6, wherein said calculating means determines, on thebasis of said information concerning the yarn withdrawal speed, a periodof time during which a yarn stopping device among the series sequence ofyarn storing devices remains actuated.
 9. Method for controlling a yarnstoring, feeding and measuring device, particularly for jet weavingmachines, having a stationary storage drum onto which an intermediateyarn store is wound by a winding-on device and from which the yarn iswithdrawn spiralling around the withdrawal end of the storage drum and aplurality of yarn stopping devices being arranged at angular intervalsaround the storage drum, wherein the yarn stopping devices arealternately actuated and de-actuated for controlling the withdrawal ofyarn from the drum, and that the yarn withdrawal speed is defined by theperiod of time during which a yarn stopping device remains actuated andby the angular distance between two yarn stopping devices subsequentlyactuated during a weft yarn withdrawal cycle.
 10. Method as claimed inclaim 9, including the step of storing information concerning the yarnstopping device actuated at the end of the last yarn withdrawal cycle.11. Method as claimed in claim 10, including the step of calculating thestopping device to be actuated at the end of the present withdrawalcycle on the basis of said stored information concerning the yarnstopping device actuated at the end of the last yarn withdrawal cycleand on the basis of an input information representing the weft yarnwithdrawal length.
 12. Method as claimed in claim 9, including the stepof determining a period of time during which a yarn stopping deviceremains actuated, on the basis of an input information concerning theweft yarn withdrawal speed.
 13. Method as claimed in claim 9, whereinthe respective angular distances between two subsequently actuated yarnstopping devices and/or the respective periods of time during which theyarn stopping devices are actuated are chosen such that the weft yarnwithdrawal speed increases at the beginning of a weft yarn withdrawalcycle, the withdrawal speed remains constant during a subsequent part ofthe weft yarn withdrawal cycle, and the weft yarn withdrawal speed isreduced at the end of the weft yarn withdrawal cycle by varying therespective periods of time during which the yarn stopping devices remainactuated and/or by varying the respective angular distances between twosubsequently actuated yarn stopping devices.